What is a characteristic of sour mash whiskey?

A defining characteristic of sour mash whiskey is that it incorporates a portion of mash from a previous distillation, which is used to help start the fermentation process. This method can result in a more consistent flavor profile and contributes to the unique sour taste. Jack Daniels is one of the most well-known brands that produces sour mash whiskey, making it a quintessential example of this category of whiskey.

Regarding the other options, while some sour mash whiskeys might include malted barley, it is not a requirement that they are made from malted barley only. The notion that sour mash whiskey is produced exclusively in Canada is incorrect, as it is primarily associated with American whiskey production, especially in Tennessee and Kentucky. Additionally, the aging requirement is not specifically tied to sour mash whiskey; it can age for varying lengths of time depending on the producer and style, but typical aging does not necessarily extend to 12 years.